Is the ‘Master Cleanse’ a detox diet or dangerous deprivation?

Consumer interest in “detox” drinks and pricey juices has skyrocketed in recent years. The “master cleanse” version has you forego food for days at a time in place of water, lemon juice, cayenne and honey or agave syrup. The goal is all around better health, including slimming down and boosting energy.

But is cleansing safe? What toxins does it get rid of? Do the positive results last just a few days? Are there negative results that last longer?